Levels of Ecological Organization in Freshwater Systems

1. Levels of Ecological Organization in Freshwater Systems Population Community Ecosystem

2. To describe the “ecosystem concept”. • To review recent advances in our understanding of the ecosystem ecology of freshwater systems, focusing on linkages between freshwater and terrestrial systems. • To expand this discussion of freshwater-terrestrial linkages by examining the community-level implications of these linkages. Freshwater Ecosystems and Aquatic-Terrestrial Linkages

3. Ecosystem = natural unit of the landscape with a “critical” level of homogeneity. • Nutrients and energy cycle within ecosystems and move among ecosystems by abiotic process and biotic processes. • > Individuals / populations / communities are different ways of packaging energy and nutrients, and offer different perspectives on how energy and nutrients move within and among ecosystems. • By tracking the input, internal cycling, and output of energy and nutrients, we can understand the fundamental role of an ecosystem in the larger landscape. The Ecosystem Concept

4. We have seen the influence of the ecosystem concept already:

5. What else can an ecosystem approach tell us about the connection between freshwater and terrestrial systems? • Are streams just plumbing the landscape? • Where does the C that supports lake productivity come from?

6. What else can an ecosystem approach tell us about the connection between freshwater and terrestrial systems? • Are streams just plumbing the landscape? N

7. The N problem

8. “Rivers deliver N to coastal ecosystems” “Streams and rivers are not N-limited”

9. The LINX project

10. Spiraling Length How far does the average N atom travel downstream before taken up by the biota? • S Low = Retentive • S High = Leaky N (Peterson et al. 2001)

11. LINX Results (Peterson et al. 2001)

12. Streams help to prevent terrestrial N from reaching coastal ecosystems… LINX Implications …especially headwater streams.

13. What else can an ecosystem approach tell us about the connection between freshwater and terrestrial systems? • Where does the C that supports lake productivity come from?

14. Allochthonous Autochthonous Where does the C that supports lake communities come from?

15. CO2 Where does the C that supports lake productivity come from? Respiration > Photosynthesis

16. The Experiment 13C (Pace et al. 2004)

17. Corrected for 13C that could have come from photosynthesis. The Results • Allochthonous C accounted for 40-55% of POC and 22-50% of zooplankton. (Pace et al. 2004)

18. Lakes themselves don’t produce enough C to support the animals that live in them. • Input of organic matter from the watershed allows for more secondary productivity than if lakes were isolated microcosms. Conclusions (Pace et al. 2004)

19. birds, bugs, and fishvs.N and C Population Community Ecosystem

20. How connected are stream and terrestrial communities?

21. Plots in and along a headwater stream on Hokkaido Island, Japan • Forest is deciduous The Experiment (Nakano and Murakami 2001)

22. Forest Stream Predator Communities

23. Physical conditions in stream and riparian zone: • Temperature • Light input • Biological conditions in stream and riparian zone: • Availability of aquatic and terrestrial invertebrate “prey” • Flux of invertebrate prey from stream-to-forest and from forest-to-stream • Proportion of “allochthonous” prey in fish and birds (i.e., prey from where the predators aren’t) (Nakano and Murakami 2001)

24. : Leaves on : Leaves off Temperature Results Daily mean temperature (ºC) (Nakano and Murakami 2001)

25. : Leaves on : Leaves off Terrestrial Predator Diet Results (Nakano and Murakami 2001)

26. : Leaves on : Leaves off Aquatic Predator Diet Results (Nakano and Murakami 2001)

27. Predator Diet Results (Nakano and Murakami 2001)

28. Both stream AND terrestrial predators use prey inputs from the other systems. Conclusions

29. Maybe “freshwater” and “terrestrial” distinctions are less useful than we thought…

30. “It does appear that on many, many different human attributes-height, weight, propensity for criminality, overall IQ, mathematical ability, scientific ability - there is relatively clear evidence that whatever the difference in means-which can be debated - there is a difference in the standard deviation, and variability of a male and a female population.” - Lawrence H. Summers President of Harvard January 14, 2005 Editorial* *The views expressed here are those of the person doing the talking.

31. Mary E. Power, UC Berkeley • Bobbi L. Peckarsky, Cornell and University of Wisconsin • Margaret A. Palmer, University of Maryland • Kate H. Macneale, NOAA • Margaret A. Palmer, University of Maryland • Emily S. Bernhardt, Duke University • Judy L. Meyer, University of Georgia • Carol L. Folt, Dartmouth College • Nancy B. Grimm, Arizona State University • Margaret B. Davis, University of Minnesota • Jane M. Hughes, Center for Riverine Landscapes, Australia Editorial*

32. “It does appear that on many, many different human attributes-height, weight, propensity for criminality, overall IQ, mathematical ability, scientific ability-there is relatively clear evidence that whatever the difference in means-which can be debated-there is a difference in the standard deviation, and variability of a male and a female population.” - Lawrence H. Summers FormerPresident of Harvard January 14, 2005 WRONG Editorial* *The views expressed here are those of the person doing the talking.